Esophageal cancer (EC) is one of the most common malignant tumors in the world, and China has the highest incidence of esophageal squamous cell carcinoma (ESCC).According to the TNM staging system of the Union for International Cancer Control (UICC) (7th Edition, 2012), EC invades the esophageal adventitia at the T3 stage; invades the pleura, pericardium and diaphragm at the T4a stage; and involves adjacent vital organs (mainly the thoracic aorta, aortic arch, trachea, tracheal bifurcation, and spine) at the T4b stage.It is considered that T3- and T4a-stage tumors can be surgically resected, while tumors at the T4b stage are not suitable for surgical resection.Therefore, it is important for physicians and patients to know whether the tumor has metastasized to adjacent organs before considering resection. The preoperative stage is unclear in many cases of progressive disease and the involvement of vital organs is only discovered by exploratory thoracotomy, because of which the resection may need to be terminated prematurely, leading to unnecessary injuries.Therefore, accurate preoperative staging of EC, especially during the later stages, is important for deciding the appropriate therapeutic option and evaluation of the prognosis.